SoundCloud groups were ways for likeminded artists and fans to form communities around common interests. There aren’t a lot of fans of (say) vintage Chicago industrial music from the early 1990s, but there are enough of them that can pool their resources and share both old material and new stuff from across the service.

People also pooled their work together regionally – especially critical in sparsely populated areas – and… well, there are a billion different uses for groups as you can imagine.